Changes

February 2025 — minor update. Information on mebendazole has been updated in line with the British National Formulary. 

Update

Goals

To support primary health care professionals to:

• Identify and manage roundworm (Ascaris lumbricoides) infestation.
• Give advice on prevention of re-infection and transmission of roundworm to others.

Outcome measures

Audit criteria

QOF indicators

QIPP - Options for local implementation

NICE quality standards

What is it?

• The roundworm Ascaris lumbricoides is the most common human intestinal worm infection worldwide. 
• Ascariasis is the term used to describe the spectrum of symptoms caused by infection with Ascaris lumbricoides. 
  • Ascaris lumbricoides is the largest roundworm found in humans — adult females grow to 20–35 cm in length and adult males to 15–30 cm. 
  • Ascariasis can also less commonly be caused by Ascaris suum cross-transmission between pigs and humans. 
• Ascaris have a wide geographical distribution but are most prevalent in tropical and subtropical areas where sanitation is poor. 
• Transmission occurs via the passing of eggs in the faeces of infected people. In areas without adequate sanitation, these eggs contaminate the soil. This can occur when contaminated vegetables are not adequately cooked, washed or peeled; from contaminated water sources; and via touching contaminated soil and not washing hands afterwards. 
  • Due to the role of contaminated soil in its transmission, Ascaris is known as a soil-transmitted helminth (STH). 
  • Ingested, infective eggs hatch in the duodenum, and the larvae invade the intestinal mucosa and are carried to the lungs in the bloodstream. 
    
    • Unfertilized eggs may be ingested but are not infective.
  • Once in the lungs, the larvae continue to mature and ascend the bronchial tree to the throat, where they are swallowed. 
  • The larvae develop into adult worms once they reach the small intestine and can live for up to 2 years.
  • Adult females can produce up to 240,000 eggs per day. 
• As eggs passed in faeces need around 3 weeks to mature in the soil before they become infective, person-to-person transmission is not possible.

[Dold, 2011; Pullan, 2014; CDC, 2019; Holland, 2022; WHO, 2023; CDC, 2023]

How common is it?

• An estimated 730–804 million people are infected with ascariasis worldwide.
  
  • Ascaris infection is most prevalent in tropical and subtropical areas (such as parts of Africa, China, South East Asia and Central, and South America) where water supplies and sanitation are poor.
  • Between 2005 and 2015, ascariasis infections were estimated to have declined by 10% to 15%. 
• In economically developed countries, ascariasis infection is generally rare.  
• The Office for Health Improvement and Disparities estimates that up to 20% of migrants from endemic countries may have helminth infections at the time of their arrival in the UK. 
• Heavy infections caused by a higher number of worms are more common in children than in adults.

[CDC, 2019; Else, 2020; OHID, 2021; Holland, 2022; WHO, 2023; CDC, 2024]

Complications and prognosis

• Complications are restricted to a small percentage of individuals with a high worm burden, although most have a small burden. In endemic areas, the majority of infections cause mild or no symptoms. 
• Complications include:
  
  • Löffler syndrome (eosinophilic pneumonitis) — respiratory symptoms such as lung infiltration, intense eosinophilia, cough, wheeze, urticaria, dyspnoea, haemoptysis, and abnormal breath sounds are observed during the larval migration through the airways 10-14 days after infection.
  • Gastrointestinal complications— upper gastrointestinal bleeding, small bowel obstruction, volvulus, intussusception, peritonitis, haemorrhagic bowel infarction, and perforation have been observed when adult parasites dwell in the lower intestine. 
  • Effects on children — nutritional deficiencies associated with roundworm infection (such as vitamin A deficiency) may lead to cognitive and growth delays in young children. Physical weakness, lack of appetite, abdominal pain, nausea, diarrhoea, and weight loss have also been observed in children with severe ascariasis.
  • Sepsis — complicated ascariasis with peritonitis or cholangitis may lead to sepsis, although the likelihood is low.
• The prognosis is generally excellent  — most infections are asymptomatic, and worms can be eradicated with antihelminth treatment. 
• Cure rates with antihelminth treatment are high.
  • A systematic review found cure rates between 92.6% and 97.3%, compared to 12.7% with placebo treatment.  
• Heavy untreated infections can cause significant morbidity and mortality — complications (such as intestinal obstruction) can be life-threatening.

[Moser, 2017; Else, 2020; BMJ Best Practice, 2023; WHO, 2023; CDC, 2024; Hon, 2024]

What are the clinical features of roundworm infestation?

Ascaris infection is often asymptomatic or presents with mild non-specific symptoms — clinical features alone cannot be used to make a diagnosis.

• Ascaris infection severity is related to the intensity of infection. People with low worm burden usually do not suffer from the infection, whereas heavy worm burden can cause a range of symptoms, including:
  • Diarrhoea and abdominal pain — in severe cases (typically those with heavy worm burdens), the person may present with acute abdomen due to small bowel obstruction, volvulus, intussusception, peritonitis, perforation, biliary colic, acute cholecystitis, acute pancreatitis, or acute cholangitis.
  • Malnutrition.
  • General malaise and weakness.
  • Impaired growth and physical development.
  • Infections of a very high intensity can cause intestinal obstruction, which should be treated surgically.
• Larvae may cause Löffler syndrome (eosinophilic pneumonitis) — a self-limiting inflammatory reaction caused by larvae migrating through the pulmonary system. It occurs within 2 weeks of the initial infection and may present with fever, wheeze, cough, dyspnoea, and/or haemoptysis.
• The most intense infections occur in children aged 5 to 15 years, causing malabsorption of nutrients and developmental delay.

Generally, Ascaris infections are self-limiting.

How should I assess a person with suspected roundworm infection?

• Take a history asking about:
  • Travel to or migration from endemic areas.
  • Clinical features including respiratory (such as cough, dyspnoea, and wheeze), gastrointestinal (such as abdominal discomfort, distension, and nausea) and systemic symptoms (such as fever).
• Examine the person looking for clinical signs of ascariasis, check:
  • Vital signs including temperature.
  • The skin for urticarial or other rash, which may be present due to migrating larvae.
  • The gastrointestinal system.
  • The respiratory system.
• Arrange appropriate investigations:
  • Send a stool sample to check for the presence of eggs. 
    • This is the most reliable way to diagnose ascariasis and should be ordered for patients suspected of intestinal ascariasis.
    • Collecting and testing 3 stool specimens on 3 different days improves detection due to variable shedding.
    • Be aware that eggs may not appear in stool for several months after exposure, as female worms do not produce eggs for over 40 days. 
  • Consider additional investigations if necessary, for example:
    • Order chest x-rays in patients suspected of having Löffler syndrome (eosinophilic pneumonitis).
    • Order abdominal X-rays in patients with signs of intestinal obstruction.
  • Consider taking a full blood count to check for eosinophilia. Patients with an eosinophil count greater than 0.4 x 10⁹ per litre should be screened according to place of exposure:
    • Anywhere in the tropics, screen by stool microscopy and Strongyloides serology.
    • In sub-Saharan Africa, screen by stool microscopy, urine microscopy, Strongyloides serology, and Schistosoma serology.
• Seek advice from an infectious disease specialist in cases where there is diagnostic uncertainty. 

What else might it be?

Alternative conditions that may present similarly to ascariasis include: 

• Asthma — repeated episodes of coughing, wheezing, chest tightness, and dyspnoea. For more information, see the CKS topic on Asthma.
• Viral gastroenteritis — self-limiting watery diarrhoea, vomiting, or both, with or without fever. Diarrhoea and vomiting are not common ascariasis symptoms. For more information, see the CKS topic on Gastroenteritis.
• Amoebiasis — usual presentation is with diarrhoea that lasts several days, weight loss, and abdominal pain.
• Salmonella infection — presents with nausea, diarrhoea, and vomiting. May also cause headaches, abdominal pain, fever, or myalgia. May be a history of eating contaminated food.
• Strongyloides infection — presents with abdominal pain, diarrhoea or constipation, weight loss, skin changes, or pulmonary issues. May be a history of travel to an endemic country.
• Pancreatitis — presents with abdominal pain that is severe and radiates towards the back. Usually accompanied by fever, nausea, and vomiting. For more information, see the CKS topics on Pancreatitis - acute and Pancreatitis - chronic
• Cholecystitis — presents with right upper quadrant pain, nausea, and positive Murphy's sign. May be a history of gallstones. For more information, see the CKS topic on Cholecystitis - acute
• Acute appendicitis — presents with mid-abdominal pain that moves to the right lower quadrant. Pain gets worse with movement. For more information, see the CKS topic on Appendicitis
• Ancylostomiasis — also known as hookworm infection. Patients with heavy infections may develop a cough characteristic of Löffler's syndrome. May also occasionally become host to dog and cat hookworms.
• Trichuriasis — also known as whipworm infection. May present with abdominal pain, bloody diarrhoea, and tenesmus. 

Scenario: Management of roundworm

From age 1 month onwards.

Mebendazole

Search strategy

Scope of search

A literature search was conducted for guidelines, systematic reviews and randomized controlled trials on primary care management of roundworm.

Search dates

November 2017 - June 2024

Key search terms

Various combinations of searches were carried out. The terms listed below are the core search terms that were used for Medline.

• exp ascaris/, exp ascariasis/
• ascariasis.tw., ascaris.tw., ascarid*.tw., roundworm*.tw., round worm*.tw., round-worm*.tw.

Sources of guidelines

• National Institute for Health and Care Excellence (NICE)
• Scottish Intercollegiate Guidelines Network (SIGN)
• Royal College of Physicians
• Royal College of General Practitioners
• Royal College of Nursing
• NICE Evidence
• World Health Organization
• Guidelines International Network
• TRIP database
• Agency for Healthcare Research and Quality
• Institute for Clinical Systems Improvement
• National Health and Medical Research Council (Australia)
• Royal Australian College of General Practitioners
• British Columbia Medical Association
• Canadian Medical Association
• Alberta Medical Association
• Michigan Quality Improvement Consortium
• Singapore Ministry of Health
• National Resource for Infection Control
• RefHELP NHS Lothian Referral Guidelines
• Medline (with guideline filter)
• Driver and Vehicle Licensing Agency
• NHS Health at Work (occupational health practice)

Sources of systematic reviews and meta-analyses

• The Cochrane Library:
  • Systematic reviews
  • Protocols
  • Database of Abstracts of Reviews of Effects
• Medline (with systematic review filter)
• EMBASE (with systematic review filter)

Sources of health technology assessments and economic appraisals

• NIHR Health Technology Assessment programme
• The Cochrane Library:
  • NHS Economic Evaluations
  • Health Technology Assessments
• Canadian Agency for Drugs and Technologies in Health
• International Network of Agencies for Health Technology Assessment

Sources of randomized controlled trials

• The Cochrane Library:
  • Central Register of Controlled Trials
• Medline (with randomized controlled trial filter)
• EMBASE (with randomized controlled trial filter)

Sources of evidence based reviews and evidence summaries

• Bandolier
• Drug and Therapeutics Bulletin
• TRIP database
• Central Services Agency COMPASS Therapeutic Notes

Sources of national policy

• Department of Health
• Health Management Information Consortium (HMIC)

Patient experiences

• Healthtalk
• BMJ - Patient Journeys

Sources of medicines information

The following sources are used by CKS pharmacists and are not necessarily searched by CKS information specialists for all topics. Some of these resources are not freely available and require subscriptions to access content.

• British National Formulary (BNF)
• electronic Medicines Compendium (eMC)
• European Medicines Agency (EMEA)
• LactMed
• Medicines and Healthcare products Regulatory Agency (MHRA)
• REPROTOX
• Scottish Medicines Consortium
• Stockley's Drug Interactions
• TERIS
• TOXBASE
• Micromedex
• UK Medicines Information

Stakeholder engagement

Our policy

The external review process is an essential part of CKS topic development. Consultation with a wide range of stakeholders provides quality assurance of the topic in terms of:

• Clinical accuracy.
• Consistency with other providers of clinical knowledge for primary care.
• Accuracy of implementation of national guidance (in particular NICE guidelines).
• Usability.

Principles of the consultation process

• The process is inclusive and any individual may participate.
• To participate, an individual must declare whether they have any competing interests or not. If they do not declare whether or not they have competing interests, their comments will not be considered.
• Comments received after the deadline will be considered, but they may not be acted upon before the clinical topic is issued onto the website.
• Comments are accepted in any format that is convenient to the reviewer, although an electronic format is encouraged.
• External reviewers are not paid for commenting on the draft topics.
• Discussion with an individual or an organization about the CKS response to their comments is only undertaken in exceptional circumstances (at the discretion of the Clinical Editor or Editorial Steering Group).
• All reviewers are thanked and offered a letter acknowledging their contribution for the purposes of appraisal/revalidation.
• All reviewers are invited to be acknowledged on the website. All reviewers are given the opportunity to feedback about the external review process, enabling improvements to be made where appropriate.

Stakeholders

• Key stakeholders identified by the CKS team are invited to comment on draft CKS topics. Individuals and organizations can also register an interest to feedback on a specific topic, or topics in a particular clinical area, through the Getting involved section of the Clarity Informatics website.
• Stakeholders identified from the following groups are invited to review draft topics:
  • Experts in the topic area.
  • Professional organizations and societies (for example, Royal Colleges).
  • Patient organizations, Clarity has established close links with groups such as Age UK and the Alzheimer’s Society specifically for their input into new topic development, review of current topic content and advice on relevant areas of expert knowledge.
  • Guideline development groups where the topic is an implementation of a guideline.
  • The British National Formulary team.
  • The editorial team that develop MeReC Publications.
• Reviewers are provided with clear instructions about what to review, what comments are particularly helpful, how to submit comments, and declaring interests.

Patient engagement

Clarity Informatics has enlisted the support and involvement of patients and lay persons at all stages in the process of creating the content which include:

• Topic selection
• Scoping of topic
• Selection of clinical scenarios
• First draft internal review
• Second draft internal review
• External review
• Final draft and pre-publication

Our lay and patient involvement includes membership on the editorial steering group, contacting expert patient groups, organizations and individuals.

Evidence exclusion criteria

Our policy

Scoping a literature search, and reviewing the evidence for CKS is a methodical and systematic process that is carried out by the lead clinical author for each topic. Relevant evidence is gathered in order that the clinical author can make fully informed decisions and recommendations. It is important to note that some evidence may be excluded for a variety of reasons. These reasons may be applied across all CKS topics or may be specific to a given topic.

Studies identified during literature searches are reviewed to identify the most appropriate information to author a CKS topic, ensuring any recommendations are based on the best evidence. We use the principles of the GRADE and PICOT approaches to assess the quality of published research. We use the principles of AGREE II to assess the quality of published guidelines.

Standard exclusions for scoping literature:

• Animal studies
• Original research is not written in English

Possible exclusions for reviewed literature:

• Sample size too small or study underpowered
• Bias evident or promotional literature
• Population not relevant
• Intervention/treatment not relevant
• Outcomes not relevant
• Outcomes have no clear evidence of clinical effectiveness
• Setting not relevant
• Not relevant to UK
• Incorrect study type
• Review article
• Duplicate reference

Organizational, behavioural and financial barriers

Our policy

The CKS literature searches take into consideration the following concepts, which are discussed at the initial scoping of the topic.

• Feasibility
  • Studies are selected depending on whether the intervention under investigation is available in the NHS and can be practically and safely undertaken in primary care.
• Organizational and Financial Impact Analysis
• Studies are selected and evaluated on whether the intervention under investigations may have an impact on local clinical service provision or national impact on cost for the NHS. The principles of clinical budget impact analysis are adhered to, evaluated and recorded by the author. The following factors are considered when making this assessment and analysis.
  • Eligible population
  • Current interventions
  • Likely uptake of new intervention or recommendation
  • Cost of the current or new intervention mix
  • Impact on other costs
  • Condition-related costs
  • In-direct costs and service impacts
  • Time dependencies
• Cost-effectiveness or cost-benefit analysis studies are identified where available. 

We also evaluate and include evidence from NICE accredited sources which provide economic evaluations of recommendations, such as NICE guidelines. When a recommended action may not be possible because of resource constraints, this is explicitly indicated to healthcare professionals by the wording of the CKS recommendation.

Declarations of interest

Our policy

Clarity Informatics requests that all those involved in the writing and reviewing of topics, and those involved in the external review process to declare any competing interests. Signed copies are securely held by Clarity Informatics and are available on request with the permission of the individual. A copy of the declaration of interest form which participants are asked to complete annually is also available on request. A brief outline of the declarations of interest policy is described here and full details of the policy is available on the Clarity Informatics website. Declarations of interests of the authors are not routinely published, however competing interests of all those involved in the topic update or development are listed below. Competing interests include:

• Personal financial interests
• Personal family interest
• Personal non-financial interest
• Non-personal financial gain or benefit

Although particular attention is given to interests that could result in financial gains or losses for the individual, competing interests may also arise from academic competition or for political, personal, religious, and reputational reasons. An individual is not obliged to seek out knowledge of work done for, or on behalf of, the healthcare industry within the departments for which they are responsible if they would not normally expect to be informed.

Who should declare competing interests?

Any individual (or organization) involved in developing, reviewing, or commenting on clinical content, particularly the recommendations should declare competing interests. This includes the authoring team members, expert advisers, external reviewers of draft topics, individuals providing feedback on published topics, and Editorial Steering Group members. Declarations of interest are completed annually for authoring team and editorial steering group members, and are completed at the start of the topic update and development process for external stakeholders.

Competing interests declared for this topic:

None.